GR: Yes, by mid 2008. But prior to that, we're going to have an online system for people to use, for which they can program applications.

JP: That seems implausibly rapid. How will you do it?

GR: Well, there are three things that need to be done.

The first is that the design that you are using for the processor, specifically the input-output systems, need to be scalable, not just in principle but in practice. Most of the proposals that have been put forward for quantum-computing architectures, in fact all of them so far, are not scalable in that sense. In our case, we believe we've found a path to real scalability in the hardware. The primary thing that needs to be overcome is this issue of how do you get information into and out of the chip. We think we've found a way around that problem.

The second thing is how you build it, and that's a fabrication issue. Part of the reason why we picked the approach that we picked is that the circuits that we're using as the basis for these things can be designed, built, and tested using standard semiconductor procedures. So we don't need to invent any new fabrication technology except for getting the process running in the first place.

The third thing, which is probably the most difficult question to answer, is this: given that we can build it and send information in and out of it, will it in fact continue to operate as a quantum computer? That's a point that we simply cannot answer at the present time because no one has been able to model systems at that level with any predictive capability whatsoever. It's too complicated. That's a question that can only be answered empirically. So our philosophy is, do a new processor every month. Say we have 12 generations per year, something doesn't appear to be working; we can fix it through iterative redesign.